The present invention relates to an apparatus for facilitating the delivery of a child during childbirth, and more specifically relates to vacuum extractors for use during childbirth.
Often, during childbirth, the birth mother cannot deliver the child without assistance from an attending physician. In some cases, all that is required is for the attending physician or other medical personnel to push down on the birth mother""s upper abdomen when she bears down during delivery. While, in other cases, it is necessary for a physician to perform a cesarean section. However, for those cases which fall between those two extremes, some sort of intermediate assistance is often required. This typically entails the use of some type of medical device to aid the mother in the delivery of the child. In some circumstances, these devices may also be used to assist a physician during particularly difficult cesarean sections.
Forceps or other similar devices are one type of device which can be used by a physician to assist a mother during childbirth. Forceps, however, tend to be bulky and difficult for the physician to operate. Moreover, the use of forceps, at the very least, is uncomfortable for the mother and child and risks injury to both.
An alternative device which can be used to assist a mother during childbirth is a vacuum extractor. A vacuum extractor generally includes a cup, which is placed onto the child""s head. A manipulation device of some sort is coupled to the cup. For example, an elongated hollow stem may be connected to the cup by which the cup may be positioned onto the child""s head and through which vacuum pressure is introduced into the cup. Alternately, a chain or traction cord may be provided, and a vacuum introduced through a vacuum stem extending outward from the cup.
The introduction of vacuum pressure into the cup results in a suction force being applied between the cup and the child""s head which adheres the cup to the child""s head. Once the cup is positioned on and adhered to the head of the child, the vacuum extractor can then be used to extract the child from the birth canal by manipulating the traction cord, or some sort of handle or other gripping device coupled to the stem of the vacuum extractor. Several different types of vacuum extractors are known such as those described in U.S. Pat. Nos. 3,202,152, 5,019,086, 5,163,944 and 5,281,229 and U.S. application Ser. No. 08/853,422.
Although vacuum extractor devices are widely used, damage to maternal or fetal tissue may still result from improper operation and manipulation of the extractor. For example, the application of excessive traction force during extraction may result in such damage. Additionally, damage to the fetus may result from undesirable torsional forces being applied to the extractor during use.
Various methods have been used to measure forces applied during delivery in controlled settings. These arrangements, however, have typically required the use of an electric current. This passage of the electric current within the mother""s body cavities is particularly troublesome in view of the fluids and mucous contained in areas such as the birth canal. Accordingly, the measuring devices have required a thorough sealing from the environment. Similarly, sanitation of such devices can be difficult, often requiring the use of additional sealing structures, such as external sleeves and the like. Further, electrical components so disposed within the body can interfere with the operation of other electrical devices necessary during delivery. As a result, such measuring devices are generally cumbersome and expensive to use, and have not typically been incorporated into commercial obstetrical vacuum extractors.
Accordingly, in view of the foregoing, it is a general object of the invention to provide a vacuum extractor which reduces the potential of injury to the fetal and maternal tissue. An additional object to is minimize the opportunity for injury to the fetus that may result from improper usage of a vacuum extractor.
It is a more particular object of the invention to provide an obstetrical vacuum extractor assembly which ultimately provides the physician with information to enable the physician to safely grasp and pull the head of the fetus without exceeding the desired tension or traction level.
Another object of the invention is to provide the physician with real time knowledge of the traction forces exerted on the fetal scalp thereby reducing the potential for the application of excessive force which can lead to injury to the child.
A further object of the invention is to provide an instrument that can be either easily sterilized for reuse or disposed of at a reasonable cost.
Another object of the present invention is to provide a vacuum extractor as characterized above which has a design that is economical to produce in that it can be manufactured in a cost efficient manner.
An additional object of the invention is to provide an obstetrical vacuum extractor that eliminates or minimizes the ability of the physician to apply a torsional force to the extractor during use.
The present invention provides these and other advantages and overcomes the drawbacks of the prior art by providing an obstetrical vacuum extractor for placement on a child""s head for use during childbirth which provides measurements of the traction or tensile force applied to the head of the fetus. An optical strain gauge is coupled to the vacuum extractor to measure the strain resulting from the application of an extraction force. The measured strain is then transmitted and converted to a readout device which provides a readable indication of the force applied, the arrangement being calibrated to correlate the measured strain to the actual extraction force.
The optical strain gauge may be of any suitable design. For example, optical strain gauges, such as those marketed by Luna Innovations, Inc. of Blacksburg, Va., have been found to be particularly suitable. The conversion to a readable indication of the applied force may be made by any appropriate arrangement either before transmission to the readout device or at the readout device itself. Preferably, the optical strain gauge is in the form of optical sensor which is connected by an optical fiber to a read out device which analyzes the signal and displays the optical signal as an indication of force. Alternately, however, the measured strain may be converted to an electrical signal at a connector plug proximal to the vacuum extractor, the electrical signal then being transmitted to the readout device. Thus, the optical strain gauge utilizes light, rather than electricity, to measure strain. Accordingly, the vacuum extractor incorporating the optical strain gauge is much safer and easier to use, and may be more economically manufactured than such an extractor utilizing traditional force measuring technologies.
The vacuum extractor includes a vacuum cup of any known design having a side wall defining a hollow interior cavity. The side wall has a side wall edge that defines a cup opening and the vacuum cup further includes a vacuum opening in communication with the interior cavity of the cup which is adapted for connection to a vacuum source. A handle or other traction assembly is coupled to the vacuum cup to allow for manipulation of the extractor. Strain may be measured at substantially any position along the extractor where a tensile or compressive force results from the application of an extractor force. According to a preferred embodiment of the invention, the handle is coupled to the cup by an elongated hollow stem, the handle being slidably mounted on the stem and retained thereon by a flange. An optical sensor is disposed about the stem, between the flange and the handle such that the sensor measures the compressive force between the flange and the handle. The measured strain is then correlated to the extraction force applied to the device by the physician during use and displayed on a readout device. The optical strain gauge may be alternately disposed, for example, along the stem, where the stem stretches slightly, or the handle, where a bending or stretching occurs.
Additionally, the handle is preferably rotatably mounted on the stem, thus minimizing or eliminating the opportunity for the physician to apply torsional forces to the extractor during use.
These and other features and advantages of the invention will be more readily apparent upon reading the following description of a preferred exemplary embodiment of the invention and upon reference to the accompanying drawings wherein: